The present invention relates in general to improved lighting fixtures and, more particularly, to an improved fluorescent lamp socket for use in environment subject to substantial vibration or shock.
Conventional fluorescent tubes or lamps have small contact pins extending outwardly from a ferrule or cap at each end of the tube. These contact pins are electrically connected to the internal electrodes of the lamp and have a diameter substantially less than that of the tube itself. Such lamps may have lengths ranging from less than 1 foot to as much as 8 feet.
Various forms of fluorescent lamp sockets are known in the art which are adapted to hold fluorescent tubes by these contact pins. In rigorous environments in which the lamps are subject to vibration and shock, the pins may be subject to breakage or damage because the entire weight of the lamp is supported by these pins. In addition, the effect of vibration and shock on a lamp placed in a conventional socket may create stresses in the lamp with respect to the socket, which often causes the contact pins to be dislodged or to momentarily break contact with the socket contacts. Such momentary break in electrical contact can cause jitter, bounce, or flicker in the tube and impair its desired light output. Such motion may further cause the filament of the cathode to break or weaken. Accordingly, it would be desirable to support a fluorescent lamp in a manner in which the tube is held firmly in place by means other than the contact pins.
With this problem in mind, the present invention is directed to a novel structure for supporting a fluorescent lamp. In accordance with the invention, the fluorescent lamp is supported in sockets by its ferrules or end caps. This results in a more secure mounting of the tube because the tube and socket become firmly coupled. At the same time, the electrical contact between the contact pins of the lamp and the contacts of the socket is more reliably maintained without the jitter, bounce, or flicker associated with lamp motion resulting from a less firm coupling. In addition, provision is made for ready insertion or removal of the tube.